MgAc₂-Modified SnO₂ Electron Transport Layer for Highly Efficient and Thermal Stable Perovskite Solar Cells

There are always defects and oxygen vacancies in SnO₂ prepared by solution methods, hindering efficient carrier transfer between SnO₂ and the perovskite in perovskite solar cells. Thus, we employed MgAc₂ to modify the interface. Carboxyl groups of MgAc₂ filled the oxygen vacancies in SnO₂, reducing its surface defect density, and Mg²⁺ partially replaced surface Sn⁴⁺, improving the properties of the SnO₂ layer. Finally, perovskite solar cells modified with MgAc₂ exhibited a significant improvement in open-circuit voltage and fill factor, improving the power conversion efficiency from 20.52% to 22.02%. Moreover, MgAc₂-devices maintained 80% of the initial efficiency after 1250 h in thermal stability tests at 85 °C and 30% relative humidity compared to control devices. This work provides a method for treating the SnO₂ electron transport layer and demonstrates the synergistic effects of Mg²⁺ and acetate ions, which can facilitate the development of efficient and stable perovskite solar cells.